Comprehensive Income (Loss) - Schedule of Accumulated Other Comprehensive Loss (Detail) $ in Millions	6 Months Ended
	Mar. 31, 2019 USD ($)
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	$ (320)
Ending balance	(120)
Foreign Currency Translation Loss
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(184)	[1]
Other comprehensive loss	(26)	[1]
Ending balance	(210)	[1]
Minimum Pension Liability Adjustment
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(9)
Ending balance	(9)
Deferred Gains On Derivative Financial Instruments
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	3
Other comprehensive loss	(9)
Ending balance	(6)
Accumulated Other Comprehensive Loss, net
Accumulated Other Comprehensive Income Loss [Line Items]
Beginning balance	(190)
Other comprehensive loss	(35)
Ending balance	$ (225)

[1] Includes historical foreign currency translation related to certain intra-entity transactions.